For some, combing the forest in search of the perfect tonewood is akin to a mystical experience. That’s certainly the case for Lorenzo Pellegrini, a master tree picker who’s been working the forest for more than 70 years. Profiled last year by BBC News, Pellegrini, now 84, was introduced to Switzerland’s Risoud Forest a half-century ago. He’s lived there ever since.

Resonance wood found by Pellegrini is used for violins, guitars, cellos and other stringed instruments. Ironically, harsh climate and extremely poor soil are among the factors that allow the Risoud Forest to produce 350-year-old resonance spruce, as compared to the typical 180-year lifespan of such trees in other regions. Slow growth means light weight combined with rigidity, the perfect combination for beautifully sounding guitar construction.

“Up in these mountains, the trees grow so slowly sometimes they stop growing altogether,” Pellegrini told reporter John Laurenson. “They just gather strength. There are trees up here that are a thousand years old.”

Pellegrini’s personal story dovetails perfectly with the spiritual aspect of divining the perfect tree for tonewood. Raised in Italy’s Abruzzo Mountains, he and his family ventured deep into the woods each year, hours from the nearest village. There, they would spend eight months working the forests. “I used to give my leftover polenta to the wolves,” Pellegrini remembers. By the time he discovered the Risoud Forest, life among the trees seemed his natural habitat.

Today, Pellegrini refers to his work in the forest as “gardening.” He regularly weeds out the beech trees that would otherwise smother the precious spruces, the best of which he harvests for top-quality instruments. “For the trees to grow slowly and regularly, you have to let them grow close together, like the hair on your head,” he observes, adding that arid conditions are key as well. “The tree’s heart should stay dry. That gives the best wood. Solid. Enormous resonance.”

Arduous though the task may be, it’s not enough to simply find the perfect tree. Assessing the best day for harvesting is imperative as well. The ideal day, writes Laurenson, comes at the end of autumn, when the moon is lowest on the horizon and furthest from Earth. It turns out that the same lunar gravitational pull that controls sea tides also tugs sap away from the tree and deep into the ground. The less sap in the tree, the better.

In addition to Pellegrini, the BBC spoke with two other men—one, a luthier; the other, a musician—both of whom who use the resonance wood found by Pellegrini. Guitar-maker Jean-Michel Capt showed Laurenson a strip of tonewood taken from a tree that was at least 350 years old—pointing out that its grain, its rings, were dead straight and extremely close together. To demonstrate the tonewood’s properties, Capt took out a wind-up musical box and played it. It emitted a thin tinkle. He then placed the box on top of the tonewood. A warm, rich, full sound filled the room.

Pellegrini and Laurenson then visited David Guignard, one of the many musicians who reside in the Risoud Forest. Guignard, who spent his childhood in the forest, says his music teacher indoctrinated him with the idea that wood is never quite dead—that it’s always reacting to changes in temperature and humidity. Seating himself by a fireplace, Guignard took out his cello and played a bit of Bach. “The best moments of my childhood were in the forest,” he says. “I listen to the crackle of the fire and the sound of cello strings making the wood sing, and I think I will never quite hear this music in the same way again.”